Manufacturing method for laminated molded materials

Abstract

[Problem] To suppress the occurrence of positional deviation in a sliding direction of respective surfaces in a laminate molded material. [Solution] This laminate molded material is obtained by laminating at least two sheets that are plastically deformable, wherein the outer surfaces of the front and back layers are flat, and on the inner surfaces of the front and back layers, or on one or both of the opposing inner surfaces of the front and back layers and one or both of the front and back surfaces of a layer sandwiched between said front and back layers, a wavy section for allowing the surfaces to engage in the sliding direction is formed. [Effect] The wavy section is formed during molding; therefore, no processing is required before or after plastic deformation, there are few restrictions on the molded shape, productivity can be improved, and manufacturing costs can be reduced.

Description

Technical Field

[0001] The present invention relates to a laminated molding manufacturing method in which at least two sheets that can be plastically deformed are laminated and corrugated portions that engage in the sliding direction between the surfaces are formed. wood

Background Art

[0002] For example, Patent Document 1 (Japanese Patent Laid-Open No. 6-297048) discloses a method of drawing and joining different materials in one step when forming a container in which different materials are laminated. That is, the method of Patent Document 1 is a laminated drawing method for forming a container-like object in which different materials are laminated, and uses a mold having one punch and a plurality of dies. Each material is placed on each die, and these materials are sequentially drawn.

[0003] Further, for example, Patent Document 2 (Japanese Patent Laid-Open No. 6-297050) discloses a pressing method for a container-like workpiece in which different materials are laminated with the outside being soft and the inside being hard. That is, the method of Patent Document 2 is to apply pressure to the peripheral end surface of the opening side of the container-like workpiece when pressing the container-like workpiece formed by laminating different materials and having a soft outside and a hard inside.

[0004] Furthermore, for example, Patent Document 3 (Japanese Patent Laid-Open No. 2003-145225) discloses a method of joining different metal materials simultaneously with deep drawing when obtaining a deep-drawn product by overlapping different metal materials. That is, the method of Patent Document 3 is to set a material in which different metal materials are overlapped with each other in a mold of a press machine, and by pushing a punch into the mold, deep drawing the material into a target shape and simultaneously joining the different metal materials to each other.

[0005] ​These conventional methods all involve joining multiple metal plates during the molding process, instead of using so-called clad materials, which are already diffusion-bonded and have the characteristic of being resistant to delamination of each layer. However, when trying to join metal plates together during the molding process to a degree comparable to clad materials, the following challenges arose.

[0006] In other words, the conventional challenges are that it is difficult to apply the high temperatures necessary to obtain clad material during the molding stage, and that in addition to the pressure applied to the metal sheets for molding, pressure is also required on the laminated metal sheets, making it difficult to maintain a balance between this molding pressure and the pressure required for joining.

[0007] Of course, there are also hot forming methods, which may overcome the challenges of high-temperature environments. However, the pressure applied to the metal sheets during forming requires careful attention depending on the product. For example, when obtaining a cup-shaped product, if the bonding pressure in the stacking (thickness) direction between the metal sheets is high, the forming pressure may be insufficient, potentially causing fracture at the boundary between the side (circumferential) surface and the bottom surface. On the other hand, if the forming pressure is too high, there is a possibility of misalignment in the sliding direction between the stacked metal sheets. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 6-297048 [Patent Document 2] Japanese Patent Application Publication No. 6-297050 [Patent Document 3] Japanese Patent Publication No. 2003-145225 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The problems we aim to solve are that conventional methods for joining laminated metal plates during molding, and the laminated molded materials obtained by these conventional methods, make it difficult to apply high temperatures during the molding process and difficult to maintain a balance between molding pressure and joining pressure, which easily leads to misalignment of the laminated metal plates in the sliding direction. [Means for solving the problem]

[0010] To solve the above problems, this Akira At least two plates capable of plastic deformation are laminated, the outer surfaces of the front and back layers are flat, and on the inner surfaces of the front and back layers, or on either or both of the inner surfaces of either or both of the opposing front and back layers and on either or both of the front and back surfaces of the layer sandwiched between these front and back layers, a repeating wavy section is formed by molding that reduces the laminate thickness while generating a plastic instability, thereby engaging in the sliding direction between the surfaces and preventing the inner and outer layers from separating from each other. What to do and did.

[0011] In this invention, "sheet" refers to the number of plates. "Laminated" refers to the state and includes everything from simply placing them on top of each other to gluing and joining. "Front and back layers" refers to the layers on both sides facing the outside of a laminated mass. On the other hand, in this invention, "layer" refers to the number of plates "before lamination" or the number of plates in a single mass when multiple plates are combined into one, and "sheet" is not equal to "layer".

[0012] Regarding the terms "layer" and "lamination," for example, if three plates are used and two of the three plates are already integrated before lamination, then in this invention, this is expressed as a total of two layers. Similarly, if three plates are used and none of the three plates are integrated before lamination, then in this invention, this is expressed as a total of three layers.

[0013] Furthermore, in the present invention, the "sliding direction" shall include "all directions" of the direction in which the plates move while rubbing against each other. That is, in the case of a cup-shaped laminated molding material, not only the opening-bottom direction but also the circumferential direction or the diagonal direction between the circumferential direction and the opening-bottom direction shall be included in the "sliding direction".

Advantages of the Invention

[0014] The present invention obtained by the manufacturing method In the laminated molding material, since the corrugated portions engage in the sliding direction between the surfaces, there is an advantage that relative displacement between them is suppressed.

Brief Description of the Drawings

[0015] [Figure 1] (a) to (c) are diagrams for explaining the manufacturing method of the laminated molding material of the present invention. [Figure 2] (a) and (b) are diagrams for explaining the corrugated portions of the laminated molding material of the present invention. [Figure 3] It is a diagram showing the results of finite element analysis regarding the ironing angle, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 4] It is a diagram showing the results of finite element analysis regarding the flow stress ratio, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 5] It is a diagram showing the results of finite element analysis regarding the work hardening index when the ironing rate (change in sheet thickness before and after ironing / sheet thickness before ironing) is 20% for the manufacturing method of the laminated molding material of the present invention. [Figure 6] It is a diagram showing the results of finite element analysis regarding the work hardening index when the ironing rate is 30% for the manufacturing method of the laminated molding material of the present invention. [Figure 7] It is a diagram showing the results of finite element analysis regarding the work hardening index when the ironing rate is 40% for the manufacturing method of the laminated molding material of the present invention. [Figure 8] It is a diagram showing the results of finite element analysis regarding the work hardening index of the hard material and the soft material when the ironing rate is 20% for the manufacturing method of the laminated molding material of the present invention. [Figure 9] It is a diagram showing the finite element analysis results when the ironing rate regarding the work hardening index of the hard material and the soft material is 30%, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 10] It is a diagram showing the finite element analysis results regarding the equivalent plastic strain rate distribution, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 11] It is a diagram showing the finite element analysis results regarding the equivalent plastic strain rate distribution when the material types are different, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 12] It is a diagram showing the finite element analysis results regarding the equivalent plastic strain rate distribution when the flow stress characteristics of the inner and outer peripheral layers and the central layer in FIG. 10 are reversed, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 13] It is a diagram showing the finite element analysis results regarding the equivalent plastic strain rate distribution when the combination of the material types in FIG. 11 is reversed between the inner and outer peripheral layers and the central layer, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 14] It is a diagram showing the finite element analysis results regarding the friction coefficient and "waviness" between the die and the outer peripheral layer, the punch and the inner peripheral layer, and between each layer, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 15] It is a diagram showing the finite element analysis results regarding the friction coefficient and "waviness" between each layer when the friction coefficients between the die and the outer peripheral layer and between the punch and the inner peripheral layer are fixed, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 16] It is a diagram showing the finite element analysis results regarding the friction coefficient and "necking" between the die and the outer peripheral layer, the punch and the inner peripheral layer, and between each layer, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 17] It is a diagram showing the finite element analysis results regarding the friction coefficient and "necking" between each layer when the friction coefficients between the die and the outer peripheral layer and between the punch and the inner peripheral layer are fixed, which was verified for the manufacturing method of the laminated molding material of the present invention. [Figure 18]This figure shows the finite element analysis results for (a) equivalent plastic strain rate and (b) z-direction velocity in the occurrence of "undulation" in the friction coefficient between the die and the outer layer when the friction coefficient between each layer is fixed, verifying the manufacturing method of the laminated molded material of the present invention. [Figure 19] This figure shows the finite element analysis results for (a) equivalent plastic strain rate and (b) z-direction velocity in the occurrence of necking in the friction coefficient between the die and the outer layer when the friction coefficient between each layer is fixed, verifying the manufacturing method of the laminated molded material of the present invention. [Figure 20] This figure shows the finite element analysis results regarding the equivalent plastic strain rate distribution at a drawing angle of 20°, verifying the manufacturing method of the laminated molded material of the present invention. [Figure 21] This figure shows the finite element analysis results regarding the equivalent plastic strain rate distribution at a drawing angle of 20°, when the combination of material types in Figure 20 is reversed for the inner / outer layers and the central layer, verifying the manufacturing method of the laminated molded material of the present invention. [Figure 22] This figure shows the finite element analysis results regarding the equivalent plastic strain distribution for a single layer and for multiple layers of the same and different types, verifying the manufacturing method of the laminated material of the present invention. [Figure 23] This figure shows the finite element analysis results for a 5-layer structure, verifying the manufacturing method of the laminated material of the present invention. [Figure 24] This figure shows the finite element analysis results for a 5-layer laminated material, which was manufactured using the present invention, with the layers stacked in a different order than shown in Figure 23. [Figure 25] This figure shows an example of the laminated molded material and its manufacturing method according to the present invention. [Modes for carrying out the invention]

[0016] This invention addresses the problem of slippage in the sliding direction between surfaces that occurred in conventional laminated materials by laminating at least two plastically deformable plates, where the outer surfaces of the front and back layers are flat, and by forming the inner surfaces of the front and back layers, or the inner surfaces of either or both of the opposing inner surfaces of the front and back layers and either or both of the front and back surfaces of the layer sandwiched between these front and back layers, while generating a plastically unstable state and reducing the thickness of the laminate, repeating wavy sections are formed that engage in the sliding direction between surfaces and prevent the inner and outer layers from separating from each other. do This improved the situation.

[0017] This invention does not focus on making it difficult for laminated plates to peel off, but rather on preventing misalignment of the planes by engaging in the sliding direction between surfaces. Furthermore, while conventional technology referred to plates as metals, this invention applies not only to materials containing metals but also to materials that can be plastically deformed, such as resins.

[0018] Furthermore, the present invention Obtained by Laminated molded materials are specialized in preventing misalignment of the planes by engaging in the sliding direction between surfaces. Therefore, when laminating plates, they may be bonded, joined, or even clad. In this invention, as defined above, if multiple plates are formed into a single mass before lamination, that mass is considered one layer.

[0019] Furthermore, the wavy portion in the present invention is any shape that engages with the sliding direction of the surfaces as described above, but as will be described later, the specific shapes that could be reproduced were, for example, a "wavy" shape in which the layer sandwiched between the front and back layers (or the inner surfaces of the front and back layers) repeatedly meanders along the molding direction, and a "constriction" shape in which thin and thick portions repeatedly occur in the layer sandwiched between the front and back layers (or the inner surfaces of the front and back layers) along the molding direction.

[0020] Furthermore, the present invention Obtained byIn the above configuration, the laminated material may have a portion that is angled relative to the portion where the corrugated portion is formed, and a flat portion may be formed in the entire layer of this angled portion. This makes sliding between the surfaces of the plates extremely difficult.

[0021] This flat portion is the present invention Obtained by If the laminated material is, for example, cup-shaped, the corrugated portion will appear at the bottom of the cup shape, and in this case, the corrugated portion will appear on the side (circumferential) surface of the cup shape. In the case of a cup-shaped laminated material, sliding between surfaces is prevented by the corrugated portion, and in addition, the corrugated portion engages with the flat portion formed at an angle to the portion where it is formed, so that the layer located on the inner circumference of the cup shape does not come off from the layer located on the outer circumference.

[0022] Book The method for manufacturing the laminated molded material of the invention involves laminating at least two plates that can be plastically deformed, placing them on a molding apparatus, and performing molding with the molding apparatus while generating a plastically unstable state and reducing the thickness of the laminate, thereby forming a repeating wavy section on the inner surfaces of the front and back layers, or on either or both of the inner surfaces of either or both of the opposing inner surfaces of the front and back layers and on either or both of the front and back surfaces of the layer sandwiched between these front and back layers, which engages in the sliding direction between the surfaces and prevents the inner and outer layers from separating from each other. ru.

[0023] Here, "generating a plastically unstable state using a molding device" means molding under conditions that create a wavy shape. Traditionally, this type of metalworking has aimed to minimize plastic instability as much as possible to achieve stable molding. Molding under plastically stable conditions essentially means making each layer flat. Therefore, conventionally, there was no pursuit of conditions for reproducing the wavy shape, and if a wavy shape was formed by chance, it was considered a defective material.

[0024] In other words, the manufacturing method of the present invention aims to actively and reliably form a wavy portion, and by performing molding while reducing the thickness of the laminate while generating a plastically unstable state, the outer surfaces of the front and back layers are flat and the appearance is comparable to conventional good materials. In fact, compared to conventional good materials, although the peel strength is lower, it is possible to obtain a laminated molded material with the unique characteristic of being less prone to misalignment in the sliding direction between surfaces.

[0025] Furthermore, in the present invention, all or two or more of the plates may be molded in a state where they are integrally formed before lamination. By doing so, the molding pressure under plastic instability conditions can be transmitted without the intervention of buffering factors, so that the corrugated portion can be reliably formed. Again, in the present invention, as explained above regarding "layers" and "lamination," for example, if two of the three plates are integrally formed "before lamination" and then "laminated," it will be referred to as "2 layers," and for example, if all three plates are not integrally formed "before lamination" and then "laminated," it will be referred to as "3 layers."

[0026] Furthermore, in the above, the present invention, (This is labeled as "Taper Angle" in Figure 1.) Forming may be performed with a scrubbing angle of 15° or less. If the scrubbing angle is greater than 15°, the range of deformation propagation between layers becomes narrower, and propagation cannot travel back and forth, which may prevent the formation of a wavy section. The lower limit of the scrubbing angle should be 2°; if the scrubbing angle is less than 2°, the scrubbing length becomes longer and the friction area becomes larger, making it unsuitable for scrubbing.

[0027] Furthermore, in the present invention, the material may be formed with a scrubbing ratio (change in plate thickness before and after scrubbing / plate thickness before scrubbing) of 10% or more. If the scrubbing ratio is less than 10%, the range of deformation propagation between layers becomes narrower, and if the amount of deformation is small, the forming pressure does not easily propagate across the front and back layers, which may prevent the formation of a wavy section. While a scrubbing ratio of 40% or more is desirable, if it is greater than 60%, the laminate thickness becomes too thin, and there is a possibility that it will break before the wavy section can be formed.

[0028] Furthermore, regarding the relationship between the cutting angle and the cutting rate, if the cutting angle is x and the cutting rate is y, then within the range of 2°≦x≦15° and 10%≦y≦60%, a wavy portion can be formed within the upper region demarcated by the straight line y=2.43x+6.62.

[0029] Furthermore, in the present invention, the material may be molded with a coefficient of friction between the surfaces of the layers set to 0.15 or higher. If the coefficient of friction between the surfaces of the layers is less than 0.15, the deformation propagation in the molding direction by the molding apparatus tends to escape, which may result in the formation of a wavy portion. In this invention, there is no upper limit to the coefficient of friction between the surfaces of the layers, as bonding and joining are also assumed for lamination. In addition, in order to set the coefficient of friction between the surfaces of the layers to 0.15 or higher, or to adjust it to a specific value that satisfies the above conditions, one or both of the contact surfaces between the layers may be roughened by wire brushing, shot peening, or the like.

[0030] Furthermore, in the present invention, molding may be performed with the coefficient of friction between the molding apparatus and the outer surfaces of the front and back layers being lower than the coefficient of friction between the surfaces of the layers. If the coefficient of friction between the molding apparatus and the outer surfaces of the front and back layers is greater than or equal to the coefficient of friction between the surfaces of the layers, localized concentration of molding pressure during deformation is likely to occur at the contact between the molding apparatus and the outer surfaces of the front and back layers, which may lead to fracture.

[0031] Furthermore, in the present invention, when laminating plates of hard and soft materials, the material may be formed with a flow stress ratio of 1.5 to 20 between the hard and soft materials. If the flow stress ratio of the hard and soft materials is less than 1.5, deformation will not occur evenly between the hard and soft materials, and as a result, a wavy portion that engages with the sliding direction between the surfaces may not be formed. On the other hand, if the flow stress ratio of the hard and soft materials is greater than 20, deformation will occur only in the soft material, and as a result, a wavy portion that engages with the sliding direction between the surfaces may not be formed. [Examples]

[0032] The following describes the results of the analysis performed on the present invention. As shown in Figure 1, the analysis involved placing a "laminated plate," which in this example is made by stacking three metal plates, into a single block, into a molding device consisting of, for example, a "die" and a "punch." The outer surfaces of the die contact surfaces (back surfaces) of the "inner circumferential layer" (for example, the back layer of the front and back layers) that contact the punch and the "outer circumferential layer" (for example, the front layer of the front and back layers) that contact the die are flat. A "wavy portion" is formed on either or both of the front and back surfaces of the opposing inner surfaces of the inner circumferential layer and the outer circumferential layer, and on the front and back surfaces of the "central layer" sandwiched between the inner and outer circumferential layers, which engages in the sliding direction between surfaces, for example, a cup shape. of" This was done to find the conditions necessary to reliably obtain "laminated molded material" during the molding process.

[0033] In the following explanation, the "inner layer" refers to the top layer in the stacked state of the plates shown in Figure 1, and is located on the inside in the cup shape; the "outer layer" refers to the bottom layer in the stacked state of the plates shown in Figure 1, and is located on the outside in the cup shape; and the "central layer" refers to the layer sandwiched between the "inner layer" and the "outer layer." The "central layer" refers to a single layer excluding the inner and outer layers, as well as a layer formed by combining, for example, three plates excluding the inner and outer layers before stacking.

[0034] The term "wavy section" refers to two phenomena in general. One is the "undulation" phenomenon, as shown in Figure 2(a), in which the central layer repeatedly meanders along the molding direction (punch protrusion direction) across the inner and outer layers. The other is the "constriction" phenomenon, as shown in Figure 2(b), in which thin and thick sections repeatedly occur at approximately the same position in the central layer along the molding direction (punch protrusion direction). In both the "undulation" and "constriction" phenomena, the shape of one or both of the opposing inner and outer layers follows the shape change of the central layer and engages in a sliding direction between the surfaces of the central layer.

[0035] ●Figure 3 shows the finite element analysis results performed on the cutting angle. The conditions were as follows: 1: Inner and outer layers "hard material" : Central layer "soft material" = 4:1 flow stress ratio (no work hardening) 2: Inner and outer layers "soft material" : central layer "hard material" = flow stress ratio of 1:4 (no work hardening) 3: Initial thickness (total 1.0mm) Inner layer: Center layer: Outer layer = 1:1:1 4: Coefficient of friction μd = 0.1 at the contact surfaces between the die and the outer layer and between the punch and the inner layer. 5: Coefficient of friction μi between the inner surface of the inner and outer layers and both outer surfaces of the central layer = adhesion *The inner layer, central layer, and outer layer are bonded together. 6. Analysis range: Squeezing angle (x-axis) 2.86°~20.0° Hazing rate (y-axis): 5%~60%

[0036] The analysis results under the above conditions shown in Figure 3 showed that "waisting" occurred when the inner and outer layers were "soft material" and the central layer was "hard material," while "undulation" occurred when the inner and outer layers were "hard material" and the central layer was "soft material." Regarding the relationship between the cutting angle and cutting rate, it can be seen that if "undulation" or "waisting" is to be stably produced without fracture, the cutting angle should be in the range of 2.86° to 5.71° and the cutting rate should be around 25% to 40%. Furthermore, if only the production of "undulation" or "waisting" is considered (fracture after production is ignored), it can be seen that the cutting rate can be 10% to 60% within the above cutting angle range.

[0037] Furthermore, according to the analysis results, if we define the plots as follows: "white circles" represent good examples where wavy and constricted areas appeared and no fracture occurred; "half-black circles" represent good examples where wavy or constricted areas appeared and no fracture occurred; "white squares" represent good examples where fracture occurred *after* wavy and constricted areas appeared; "half-black squares" represent good examples where fracture occurred *after* wavy or constricted areas appeared; "black circles" represent poor examples where no fracture occurred but no wavy areas also appeared; and "black squares" represent poor examples where no wavy areas appeared and only fracture occurred, then it was found that the poor and good examples can be explained as follows based on the relationship between the cutting angle and the cutting rate.

[0038] In other words, good examples are, Within the range of 2°≦x(squeezing angle)≦15° and 10%≦y(squeezing rate)≦60% It manifests within the upper region demarcated by the line y = 2.43x + 6.62.

[0039] ●Figure 4 shows the finite element analysis results for the flow stress ratio, and Figures 5 to 7 show the results for the work hardening index (n-value). The conditions were as follows: 1: Conditions 3-5 in Figure 3 2: No work hardening is shown in Figure 4. Figures 5-7 show exponential hardening (however, the n-value is the same for hard and soft materials). *Vertical n value = (Inner layer n value × Initial thickness ratio) + (Outer layer n value × Initial thickness ratio) (Median n value × initial thickness ratio) 3. The cutting angle was set to approximately 2.86° (an angle of 20 in the vertical direction and 1 in the radial direction). 4: The training rate is changed in the range of 0-60% in Figure 4. Figure 5 represents 20%, Figure 6 represents 30%, and Figure 7 represents 40%. *The triangles, rhombuses, stars, and hearts in Figures 4-7 are based on the yield strength ratio and work hardening characteristics of each material.

[0040] Analysis under the conditions shown in Figure 4 revealed that "necking" occurred across a wide range of extrusion rates when the flow stress ratio was in the range of 1.5 to 10, and "undulation" occurred across a wide range of extrusion rates when the flow stress ratio was in the range of 1.5 to 20. Furthermore, it was found that extrusion occurred stably regardless of the flow stress ratio (except for 1) if the extrusion rate was 10% or higher.

[0041] The analysis results under the above conditions shown in Figures 5 to 7 revealed that when the flow stress ratio was in the range of 1.5 to 10, "necking" occurred in the range of 0.00 to 0.20 of the work hardening index, and when the flow stress ratio was in the range of 1.5 to 20, "undulation" occurred in the range of 0.00 to 0.25 of the work hardening index. Furthermore, it was found that by increasing the ironing rate to 30% or 40%, "necking" and "undulation" occurred even at high work hardening index levels.

[0042] ●Figures 8 and 9 show the finite element analysis results performed on the work hardening indices of hard and soft materials. The conditions were as follows: 1: Conditions 3-5 in Figure 3 2: Conditions in Figures 4-7 3 3: The yield strength ratio of hardwood to softwood was set to 4:1. 4. The rate of harsh training was set to 20% in Figure 8 and 30% in Figure 9.

[0043] The analysis results under the above conditions shown in Figures 8 and 9 show that when the work hardening index of the hard material is in the range of 0.00 to 0.15, "constriction" and "undulation" occur when the work hardening index of the soft material is in the range of 0.00 to 0.35. Furthermore, it can be seen that when the ironing rate is increased to 30%, the range in which both "constriction" and "undulation" occur expands to a work hardening index of 0.10 for the hard material when the work hardening index of the soft material is in the range of 0.00 to 0.15.

[0044] ●Figure 10 shows the finite element analysis results for the equivalent plastic strain rate distribution. The conditions were as follows: 1: Conditions 3-5 in Figure 3 2: Conditions in Figures 4-7 3 3. The rate of harsh training was set at 30%. 4: Flow stress Inner and outer peripheral layers: C1020-1 / 2H (n=0.088) Central layer: A1050-H24 (n=0.033)

[0045] Analysis under the conditions shown in Figure 10 revealed that "undulation" occurs when the stroke s = 26 mm or more.

[0046] ●Figure 11 shows the finite element analysis results for the equivalent plastic strain rate distribution when different material types are used. The conditions were as follows: 1: Conditions 3-5 in Figure 3 2: Conditions in Figures 4-7 3 3: Condition 3 in Figure 10 4: Flow stress (a) Inner and outer peripheral layers: C1020-1 / 2H (n=0.088) Central layer: A1050-H24 (n=0.033) (b) Inner and outer peripheral layers: SUS430 (n=0.189) Central layer: A1050-H24 (n=0.033) (c) Inner and outer peripheral layers: Ti-JIS type 1 (n=0.305) Central layer: A1050-H24 (n=0.033)

[0047] As a result of the analysis under the above conditions shown in Figure 11, "undulation" occurred even when different types of material were used, as shown in Figures (a) to (c). It was found that the equivalent plastic strain rate distribution became intersecting (zigzag) in the ironed section just before the occurrence of undulation for a stroke s=26mm, and after the occurrence for a stroke s=28mm.

[0048] ●Figure 12 shows the finite element analysis results for the equivalent plastic strain rate distribution when the flow stress characteristics of the inner and outer layers and the central layer in Figure 10 are reversed. The conditions were as follows: 1: Conditions 3-5 in Figure 3 2: Conditions in Figures 4-7 3 3. The rate of harsh training was set at 40%. 4: Flow stress Inner and outer peripheral layers: A1050-H24 (n=0.033) Central layer: C1020-1 / 2H (n=0.088)

[0049] The analysis results under the above conditions shown in Figure 12 revealed that a "waistline" appears when the stroke s = 26 mm or more.

[0050] ●Figure 13 shows the finite element analysis results for the equivalent plastic strain rate distribution when the material combinations in Figure 11 are reversed for the inner and outer layers and the central layer. The conditions were as follows: 1: Conditions 3-5 in Figure 3 2: Conditions in Figures 4-7 3 3: Condition 3 in Figure 10 4: Flow stress (a) Inner and outer peripheral layers: A1050-H24 (n=0.033) Central layer: C1020-1 / 2H (n=0.088) (b) Inner and outer peripheral layers: A1050-H24 (n=0.033) Center layer: SUS430 (n=0.189) (c) Inner and outer peripheral layers: A1050-H24 (n=0.033) Central layer: Ti-JIS type 1 (n=0.305)

[0051] As a result of the analysis under the above conditions shown in Figure 13, a "constriction" occurred as shown in Figures (a) to (c). It was found that the equivalent plastic strain rate distribution in the twisted section became intersecting (zigzag) before the occurrence of the constriction at a stroke of s=26mm, and after the occurrence of the constriction at a stroke of s=34mm.

[0052] ●Figure 14 shows the finite element analysis results regarding the "undulation" in the friction coefficients (μd) between the punch and the inner layer, and between the die and the outer layer, as well as the friction coefficients (μi) between each layer. The conditions were as follows: 1: Condition 3 in Figure 3 2: Conditions in Figures 4-7 3 3. The rate of harsh training was set to 20% in (a) and 30% in (b). 4: Condition 4 in Figure 10

[0053] The analysis results under the above conditions shown in Figure 14 show that when the wiping rate is 20% (Figure (a)), if the friction coefficient μd between the punch and the inner layer and between the die and the outer layer is high, the friction coefficient μi between each layer must also be high for "undulation" to occur. In Figure (b), when the wiping rate is 30%, the friction coefficient μd between the punch and the inner layer and between the die and the outer layer is almost 0, and "undulation" occurs only under limited conditions such as when the friction coefficient μi between each layer is 0.4 to 0.5.

[0054] ●Figure 15 shows the finite element analysis results for the friction coefficient (μi) between each layer and the "undulation" when the friction coefficient (μd) between the punch and the inner layer and between the die and the outer layer are fixed. The conditions were as follows: 1: Conditions 3 and 4 in Figure 3 2: Conditions in Figures 4-7 3 3: Conditions 3,4 in Figure 10 4: Stroke s = 28mm

[0055] The analysis results under the above conditions shown in Figure 15 showed that "undulation" occurred when the friction coefficient μi between each layer was greater than the friction coefficient μd between the punch and the inner layer, and between the die and the outer layer. Furthermore, it was found that in all cases of friction coefficient μi between each layer, localized strain concentration occurred in the outer layer, and fracture tended to occur, especially when the friction coefficient μi between each layer was low (even with a friction coefficient μi of 0.5, fracture would occur if the stroke was advanced further).

[0056] ●Figure 16 shows the finite element analysis results regarding the "necking" in the friction coefficients (μd) between the punch and the inner layer, and between the die and the outer layer, as well as the friction coefficients (μi) between each layer. The conditions were as follows: 1: Condition 3 in Figure 3 2: Conditions in Figures 4-7 3 3: Condition 3 in Figure 14 4: Condition 4 in Figure 12

[0057] As shown in Figure 16, the analysis under the above conditions revealed that, as shown in Figure 16(a), when the wiping rate is 20%, the friction coefficient μd between the punch and the inner layer and between the die and the outer layer is almost 0, and "necking" occurs only in a limited range where the friction coefficient μi between each layer is 0.05 to 0.1. As shown in Figure 16(b), when the wiping rate is 30%, it was found that if the friction coefficient μd between the punch and the inner layer and between the die and the outer layer is high, the friction coefficient μi between each layer must also be high for "necking" to occur.

[0058] ●Figure 17 shows the finite element analysis results for the friction coefficient (μi) between each layer and the "necking" when the friction coefficient (μd) between the punch and the inner layer and between the die and the outer layer are fixed. The conditions were as follows: 1: Conditions 3 and 4 in Figure 3 2: Conditions in Figures 4-7 3 3: Condition 3 in Figure 10 4: Condition 4 in Figure 12 5: Stroke s = 38mm

[0059] The analysis results under the above conditions shown in Figure 17 revealed that when the friction coefficient between layers μi ≥ 0.3, "necking" occurred. However, in all cases where the friction coefficient between layers μi was high, the strain was high and the material tended to fracture easily.

[0060] ●Figure 18 shows the finite element analysis results for (a) equivalent plastic strain rate and (b) z-direction velocity in the occurrence of "undulation" between the friction coefficients (μd) of the punch and inner layer and between the die and outer layer, when the friction coefficient (μi) between each layer is fixed. The conditions were as follows: 1: Conditions 3 and 4 in Figure 3 2: Conditions in Figures 4-7 3 3: Conditions 3 and 4 in Figure 10 4: Coefficient of friction between layers μi = 0.12

[0061] As shown in Figure 18, the analysis under the above conditions revealed that even when the friction coefficient between each layer was set to μi = 0.12, the boundary line of the distribution in the rubbing section remained zigzag after the "undulation" occurred until fracture occurred.

[0062] ●Figure 19 shows the finite element analysis results for (a) equivalent plastic strain rate and (b) z-direction velocity in the occurrence of "necking" between the friction coefficient (μd) of the punch and inner layer and between the die and outer layer, when the friction coefficient (μi) between each layer is fixed. The conditions were as follows: 1: Conditions 3 and 4 in Figure 3 2: Conditions in Figures 4-7 3 3: Condition 3 in Figure 10 4: Condition 4 in Figure 12 5: Condition 4 in Figure 18

[0063] As shown in Figure 19, the analysis under the above conditions revealed that even when the friction coefficient between each layer was set to μi = 0.12, the boundary line of the distribution in the twisted area remained zigzag after the "constriction" occurred until fracture.

[0064] ●Figure 20 shows the finite element analysis results for the equivalent plastic strain rate distribution at a scrubbing angle of 20°. The conditions were as follows: 1: Conditions 3 and 4 in Figure 3 2: The cutting angle was set to 20°. 3: Conditions 3 and 4 in Figure 10

[0065] The analysis results under the above conditions shown in Figure 20 show that "undulation" did not occur at a squeezing angle of 20°.

[0066] ●Figure 21 shows the finite element analysis results for the equivalent plastic strain rate distribution at a drawing angle of 20°, when the combination of material types for the inner and outer layers and the central layer is reversed compared to Figure 20. The conditions were as follows: 1: Conditions 3 and 4 in Figure 3 2: Condition 2 in Figure 20 3: Condition 3 in Figure 10 4: Condition 4 in Figure 12

[0067] The analysis results under the above conditions shown in Figure 21 show that no "constriction" occurred at a squeezing angle of 20°.

[0068] ●Figure 22 shows the finite element analysis results for the equivalent plastic strain distribution in the case of a single layer made from one plate and in the case of a three-layer structure made from three plates of the same type. The conditions were as follows: 1: Initial thickness The single layer is 1.0 mm thick. The three layers are arranged in a ratio of inner layer:middle layer:outer layer = 1:1:1, totaling 1.0 mm. 2: Material type and layer structure (a), (d) A1050-H24 Single layer (b), (e) SUS430 single layer (c), (f) A1050-H24 3 layers (g) Inner and outer peripheral layers: C1020-1 / 2H, center layer: A1050-H24 3 layers 3: Squeezing angle (a)~(c) Approximately 2.86° (angle of 20 in the height direction and 1 in the radial direction) (d)~(g) 20° 4: Condition 3 in Figure 10 5: Condition 4 in Figure 15 6: Condition 4 in Figure 3 7: In the case of the above three layers (c), (f), and (g): Condition 5 in Figure 3

[0069] The analysis results under the above conditions shown in Figure 22 revealed that the strain distribution of the striped pattern is influenced by factors such as the use of different materials, the multi-layered structure, and the plastic instability caused by the ironing angle.

[0070] ●Figure 23 shows the finite element analysis results for the equivalent plastic strain rate distribution when five plates are arranged in five layers. The conditions were as follows: 1: Initial thickness Each plate has a thickness of 0.2 mm, for a total thickness of 1.0 mm. 2: Material type and layer structure C1020-1 / 2H (referred to as C), A1050-H24 (referred to as A) Lamination by bonding C / A / C / A / C in order from the inner layer. *C (or A / C / A) in A / C / A is positioned as the central layer. 3: Friction coefficient μd = 0.1 between the punch and the inner layer, and between the die and the outer layer. The coefficient of friction between each layer μi = fixed 4: Hazing rate (a)~(c) 30% (d), (e) 40%

[0071] As a result of the analysis under the above conditions shown in Figure 23, when five plates were made into five layers, with a squeezing rate of 30% as shown in Figures (a) to (c), "undulation" and "constriction" occurred in C of the A / C / A layer which was the central layer, and "undulation" occurred in A of the A / C / A layer which was the central layer. On the other hand, with a squeezing rate of 40% as shown in Figures (d) and (e), "constriction" occurred in C of the A / C / A layer, and "undulation" occurred in A of the A / C / A layer which was the central layer.

[0072] ●Figure 24 shows the finite element analysis results for the equivalent plastic strain rate distribution when five plates are stacked in a different stacking order than in Figure 23. The conditions were as follows: 1: Condition 1 in Figure 23 2: Material type and layer structure C1020-1 / 2H (referred to as C), A1050-H24 (referred to as A) Lamination by bonding in the order of A / C / A / C / A from the inner layer downwards. *A (or C / A / C) in C / A / C is positioned as the central layer. 3: Condition 3 in Figure 23 4: Hazing rate (a)~(c) 30% (d)~(f) 40%

[0073] As a result of the analysis under the above conditions shown in Figure 24, in the 5-layer material, when the ironing rate shown in Figures (a) to (c) was 30%, "undulation" occurred only in the upper half of A in the central layer C / A / C, and furthermore, "constriction" occurred only in the upper half of C in the central layer C / A / C. On the other hand, when the ironing rate shown in Figures (d) to (f) was 40%, "undulation" occurred only in the upper half of A in the central layer C / A / C, and furthermore, "constriction" occurred only in the upper half of A in the central layer C / A / C.

[0074] ●Figure 25 shows a wavy section and a flat section, based on the above finite element analysis. ta product Here is an example of the conditions used when actually manufacturing layered molded material. ·Inner and outer peripheral layers: SUS430, center layer: A1050-H24 ·Initial plate thickness ratio: total 1.0mm, inner and outer peripheral layers: 0.3mm, center layer: 0.4mm • Lamination: Simply stacking layers (a condition where a slight "undulation" occurs in the central layer in finite element analysis) • Hazing rate: 35% • Yield strength ratio of SUS430 / A1050-H24: Approximately 4 ·Work hardening index n=0.189(SUS430),0.033(A1050-H24) • Contact surfaces of each layer: Roughened using a grinder before lamination. *(Friction coefficient between layers μi ≥ 0.15)

[0075] Furthermore, similar results were obtained under conditions in which the following aspects of the conditions shown in Figure 25 were changed. ·Inner and outer peripheral layers: C1020-1 / 2H, central layer: A1050-H24 • Yield strength ratio of C1020-1 / 2H / A1050-H24: approximately 2.4 ·Work hardening index n=0.088(C1020-1 / 2H),0.033(A1050-H24)

[0076] From the verification using the finite element analysis described above, it was found that in forming a so-called cup shape by laminating metal plates to form, for example, three layers (inner layer, central layer, and outer layer), the formation process, which involves a reduction in overall thickness, does not cause hard and soft materials to deform at the same rate during plastic processing. Instead, regardless of whether it is the inner or outer layer of the lamination, a localized and periodic plastic instability occurs in the deformation rate. This results in repeated "wavy sections" ("undulations," "constrictions") that engage with each other in the direction of sliding between the surfaces of the inner and outer layers that are in contact with the central layer and the central layer itself.

[0077] The following are the findings from finite element analysis regarding axially symmetric (circular in plan view) ironing processes: The deformation velocity is zero at the center of the axis (center of the disk) and at the bottom surface of the cup shape (front part of the deformation) in this example after deformation. The cup-shaped opening (rear part of the cutting area) is the edge of the disc, and there is no constraint on the edge of the disc. Since the deformation starts from the outer layer, the starting point of plastic deformation is the outer layer. Due to the reaction force and shape constraints imposed by the punch, the inner layer is then affected, and the plastic deformation behavior (bending, thickness change) of the central layer is determined by the influence of the plastic deformation of the inner and outer layers.

[0078] The shear force to the rear and the compressive force in the thickness direction resulting from plastic deformation from the inner and outer layers are transmitted to the central layer via interlayer friction. If no slip occurs between layers, the shear force to the rear is transmitted between layers without reduction. If slip occurs between layers, the shear force to the rear is transmitted between layers with a decrease, and further displacement occurs in the height direction.

[0079] Whether a thickness change exceeding the strain ratio occurs in the inner, central, or outer layers depends on what state is stable overall (minimum strain energy). When slip occurs between layers, frictional forces are generated between the layers, and a portion of the deformation energy is dissipated as frictional energy, thus changing the overall stability conditions. This is because it changes depending on various processing condition parameters such as the flow stress ratio, deformation state, and friction coefficient. Determining these stability conditions is difficult through theoretical calculations, so in this invention, instead of finding the stability conditions through theoretical calculations, the conditions under which plastic instability occurs were found through discretization and iterative convergence calculations such as finite element analysis.

[0080] In molding processes that result in a so-called cup shape by reducing the overall wall thickness, the outer layer is often more prone to being molded than the inner layer, regardless of whether or not a "wavy section" is formed. • When the twisting angle increases, the "wavy region" does not appear. This is because the plastic deformation region narrows, and the periodic fringe pattern seen in the equivalent plastic strain rate distribution when the wavy region appears (small twisting angle) is not formed (Figures 20 and 21).

[0081] The following points were revealed after finite element analysis regarding the occurrence of "undulation" in axisymmetric ironing when the inner and outer layers are made of hard material and the central layer is made of soft material. • After the "undulation" occurred (Figure 10, when the cutting rate was 30%), the thickness of the central layer was almost uniform at 0.234 mm (= cutting rate of 30%), and the cutting rate was also 30%. On the other hand, the inner and outer layers were non-uniform, ranging from 0.198 to 0.262 mm.

[0082] • The higher the erosion rate and the higher the flow stress ratio (hard material / soft material), the greater the "undulation" undulation. However, the flow stress ratio is approximately 1.5 to 20 (Figure 4).

[0083] The following points were revealed after finite element analysis regarding the occurrence of "necking" in axisymmetric ironing when the inner and outer layers are made of soft material and the central layer is made of hard material. • The thickness after constriction (Figure 12, when the cutting rate is 40%) is periodically non-uniform in the central layer, ranging from 0.173 to 0.230 mm (= cutting rate of 30 to 50%). On the other hand, the inner and outer layers are periodically non-uniform, ranging from 0.183 to 0.216 mm (= cutting rate of 35 to 45%). However, the thickness of the inner and outer layers is approximately equal in the same height direction.

[0084] • The higher the degree of deformation and the higher the flow stress ratio (hard material / soft material), the greater the "necking" undulation. However, the flow stress ratio is approximately 1.5 to 10 (Figure 4).

Claims

1. A method for manufacturing a laminated molded material comprising at least two plates capable of plastic deformation laminated together, wherein the outer surfaces of the front and back layers are flat, and the inner surfaces of the front and back layers, or the inner surfaces of either or both of the opposing inner surfaces of the front and back layers and either or both of the front and back surfaces of the layer sandwiched between these front and back layers, are formed by molding that reduces the laminate thickness while generating a plastic instability, thereby creating repeated wavy sections that engage in the sliding direction between surfaces and prevent the inner and outer layers from separating from each other.

2. A method for manufacturing a laminated molded material according to claim 1, wherein a portion having an angle with respect to the portion where the wavy portion is formed is formed, and a flat portion is formed in the entire layer of the portion having this angle.

3. A method for manufacturing a laminated molded material, comprising: stacking at least two plates that can be plastically deformed; placing them in a molding apparatus; and performing molding with the molding apparatus while generating a plastically unstable condition and reducing the thickness of the laminate, thereby forming a laminated molded material in which the outer surfaces of the front and back layers are flat, and repeating wavy sections are formed on the inner surfaces of the front and back layers, or on either or both of the inner surfaces of either or both of the opposing inner surfaces of the front and back layers and either or both of the front and back surfaces of the layer sandwiched between these front and back layers, which engage in a sliding direction between surfaces to prevent the inner and outer circumferential layers from separating from each other.

4. The method for manufacturing a laminated molded material according to claim 3, wherein the molding is performed with all or two or more of the plates integrated together before lamination.

5. The method for manufacturing a laminated molded material according to claim 3 or 4, wherein the molding is performed by ironing, and the molding is performed with an ironing angle of 15° or less.

6. A method for manufacturing a laminated molded material according to any one of claims 3 to 5, wherein the molding is performed by ironing, and the molding is carried out with an ironing rate of 10% or more.

7. A method for manufacturing a laminated molded material according to any one of claims 3 to 6, wherein the molding is performed while the coefficient of friction between the surfaces of the layers is 0.15 or more.

8. A method for manufacturing a laminated molded material according to any one of claims 3 to 7, wherein the molding is performed in a state in which the coefficient of friction between the molding apparatus and the outer surfaces of the front and back layers is lower than the coefficient of friction between the surfaces between the layers.

9. A method for manufacturing a laminated molded material according to any one of claims 3 to 8, wherein when a hard material and a soft material are laminated, the molding is performed with the flow stress ratio between the hard material and the soft material set to 1.5 to 20.

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